Saturday, February 9, 2013

Conscience Lighting Decisions

     I got a call the other day from a guy with whom I occasionally work.  He wanted to know what the regulations were concerning lighting in a parking lot.  I commenced to explain the lumen maximums and the need to hood the fixtures around the edges of the property, and then he let me know that he was actually asking if lighting was required for a parking lot within this jurisdiction.  Although this seems like an odd question because there are many instances where a parking lot would not have use after dark and not need lighting, some jurisdictions do require it.
     More frequently though, I am likely to have a client that demands lighting.  Sometimes this demand is driven by his liability insurance concerns.  More frequently, though, this demand is driven by the perception that adding lighting will make a site safer.
     In a parking lot or on a site where a good deal of nighttime pedestrian traffic is anticipated, this is absolutely correct.  Lighting is needed to allow people to move safely from place to place.  Very few people are adept at walking easily in the total dark and it is undesirable to allow people to be in a basically public area stumbling around in the dark.
     This does not mean that these places have to be lighted as if it were daytime.  You do not need massive amounts of light to move safely around outside after dark.  The human eye is quite capable of adapting to a dimmer light.  In fact, brightly lighting a parking lot or a site actually causes a number of safety problems.
     A brightly lit area in the darkness creates an area of deep contrasts and shadows.  The bright area from lights abruptly ends into darkness which creates a perfect hiding place.  Because the human eye has dilated in response to the light, it is unable to see into the darkness.  This means that a criminal does not even need to really hide.  They can actually stand in the deep shadow in dark clothing just past the pool of light and be completely obscured.  It terms of stopping crime, it is much better to have a dimly lit site that is lit over more of the site than to have a concentrated brightly lit area like a parking lot.
     As it takes some time for the eye to adjust to darkness, a brightly lit area can also lead to a greater likelihood of injury.  Walk out of the bright pool of light and into the unlit area and you are more blinded than if there had been no light on the site at all.  Again, a dimly lit area is a better choice.  The photo to the right illustrates this situation.  The area under the light is very brightly lit, but just beyond the pool of light is complete darkness.  Anyone walking out of the pool of light and into the deep shadow will be completely blind until their eyes have a chance to adjust and even after that point, they will be affected with each glance toward the lighted area.
     Excessive lighting also is a huge waste of energy and money.  Why use excessive energy to create a dangerous situation when you can use considerably less to create a safer one.  Those light fixtures and poles are also costly.  Why not save your budget and create a better situation at the same time.
     The next time you are compelled to light an area, whether it is your driveway and walk or a parking lot, stop and consider the actual need.  The area might need to be lit, but it might not need to be brightly lit.

No comments:

Post a Comment